I'd say that sanguinis promissa gloria is grammatical, but not quite what you should use.
It means roughly "the promised glory of blood".
This doesn't convey the message you have, but is pretty close.
The verb promittere has various forms like promitto and promissa and promittis. These are all valid forms, but they mean different things. Choosing the correct form is something that Google Translate consistently fails with.
The verb promittere (sometimes listed as promitto) can mean a number of things, including the literal meaning "to send forward".
The English "to promise" is derived from this, but the meaning is not as close as one might think.
I think a better verb for promising is polliceri (sometimes listed as polliceor).
I think sanguis is a good word for "blood", including this kind of use.
It is used to denote descent, bloodline, origin, and things in that flavor, and that is certainly useful.
One should be careful with the different kinds of blood, as for example cruor means the blood that flows out a wound.
One might say that sanguis and cruor are both "blood", but one refers to life and the other to death.
If glory comes from bloodshed instead of bloodline, then cruor is your word.
Gloria is a decent translation for "glory".
There might be better words, but it's certainly understandable.
I encourage you to look up these words and other potential candidates in any online Latin dictionary.
A more direct translation leads me to:
Sanguis (cruor) pollicetur gloriam.
Blood promises glory.
But for a motto I find that nominal phrases without explicit verbs often work better:
Gloria sanguine (cruore) pollicita.
Glory promised by blood.
Choose sanguis or cruor depending on what you need.
I recommend using sanguis unless you specifically want cruor.